Fundamental research on low-loss X-ray multi-layer waveguide and high performance X-ray functional device

通过理论和实验验证，我们在x射线波导和功能器件的基础研究中取得了良好的成果。假设原子是介电圆柱体，用边界元法分析了x射线在原子水平上的反射和散射特性。为了减少计算时间，我们采用了并行边界元算法，现在我们可以用大约150个圆柱的模型进行分析。在分析原子等效折射率时，考虑到电子在原子内的运动，可以采用非均匀折射率散射模型来分析单个原子的x射线散射。该模型采用受x射线影响的电子能级作为参数。证实了由x射线激发的电子与原子内指数分布之间的强相关性，以及x射线强度分布分析结果与原子内指数分布之间的相关性。并与实验得到的材料的折射率分布进行了比较，证实了所得折射率分布具有相似的色散特性，表明所得结果的正确性。除了本研究中使用的Si/Mo、Pt作为x射线多层反射镜的材料外，我们还选择了Ag/La和Rh/Ce，并探索了波长、层数和入射角的关系。假设入射角在光纤传输时接近临界角，对反射率进行了优化，得到了良好的反射率特性。我们研究了锥形波导探头的聚焦特性。考虑了三种不同的锥形波导结构，即线性型、凹型和凸型。结果表明，当输出芯尺寸小于x射线波长时，首选线性锥度；当输出锥度尺寸大于x射线波长时，首选凸型锥度。对随机折射率介质的x射线梯度光纤中的电磁场进行了统计研究。我们发现，当波动的相关长度大于光斑尺寸时，损耗随光纤半径的变化很快；当相关长度小于波长时，损耗虽小但随半径的变化不大。我们计算了二维Mo和c晶体的光子带结构，但没有确定光子带隙。光子带结构为x射线波导提供了基础。未来，我们必须研究如何减少x射线波导上的损耗。根据研究项目的结果，研究低损耗的x射线波导和高性能的功能器件已经成为可能。少

Based on theoretical and experimental examination, we could obtain good results in fundamental research of X-ray waveguides and functional devices.1.Making the hypothesis of atom to be a dielectric cylinder, we analyzed reflection and scattering characteristics of X-rays at the atomic level,using BEM.We applied parallel BEM algorithm to reduce the computation time, and we are now able to analyze with the model having about 150 cylinders.2.Considering the motion of electron within the atom for analyzing equivalent refractive index of atom, we could analyze X-ray scattering of a single atom using an inhomogeneous refractive index scattering model. Energy level f electron affected by X-rays is used as a parameter in this model. Strong correlation between electrons excited due to X-rays and index distribution, and also the correlation of results of X-ray intensity distribution analysis with the index distribution within the atom were confirmed. Further, by the comparison with refractive in … More dex of materials obtained experimentally, it was confirmed that the derived refractive index distribution shows similar dispersion characteristics, and this indicates the appropriateness of the obtained results.3.In addition to Si/Mo, Pt which had been used for this research as materials of the X-ray multi-layer mirror, we chose Ag/La and Rh/Ce and explored the dependence of wavelength, number of layers and incident angle. Making the hypothesis of the incident angle to be near critical angle as in fiber transmission, we optimized the relectivity, which resulted in good reflectivity characteristics.4.We examined the focussing characteristics of tapered waveguide probes. Three different tapered waveguide configurations have been considered, viz., linear type, concave type and convex type. According to the results, it was concluded that linear taper would be preferred when the output core size is smaller than the wavelength and convex type taper would be preferred when the output taper size becomes larger than the wavelength of X-ray used.5.The electromagnetic fields in X-ray gradient fiber with random refractive index media are studied statistically. We found that the loss varies rapidly with the radius of the fiber when the correlation length of the fluctuation is larger than the spot size, and the loss becomes small but does not varies very much with the radius when the correlation length is smaller than the wavelength.6.We have calculated photonic band structures for 2-dimensional crystals of Mo and C. The difinite photonic band gap is not confirmed. The photonic band structure provides a basis for the X-ray waveguide.In future, we must examine reduction of loss on X-ray waveguides. According to the results of research project, it has become possible to study low-loss X-ray waveguides and functional devices of high-performance. Less